The highway widening project that's slowed traffic along the already slothful 405 freeway for the past four years, and brought us the revelatory event known as "Carmageddon", hasn't been all bad news. It offers a glimpse of the city's oldest rocks.

"If you’re among the 300,000 or so commuters who crawl through the Sepulveda Pass every day, you’ve surely noticed the $950-million construction project that is adding an extra lane to both sides of the 405 Freeway. You’ve no doubt spied the giant earthmovers slicing through the mountain. And at some point your gaze has rested on the eight-story-tall retaining walls doing their best to hold back the Santa Monica Mountains."

"Although expensive, inconvenient, and (some argue) unnecessary, those new cuts through the mountains thrill me," writes Arthur G. Sylvester. "I’m a geologist, and the massive expansion project has given me a temporary glimpse into the very anatomy of this mountain range that bisects Los Angeles, separating West L.A. from the Valley, downtown from Burbank. You may not know it by looking at the sleek cars streaming over the pass or the helicopters beating overhead, but the last time some of these rocks touched air, dinosaurs walked the Earth."

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